#define _CRT_SECURE_NO_WARNINGS
//计算n的阶乘
#include <stdio.h>
int main()
{
	int n,sum=1;
	scanf("%d", &n);
	while (n >0)
	{
		sum *= n;
		n--;
	}
	printf("n!=%d\n",sum);
	
	return 0;
}